Brown resigned from the Federal Emergency Management Agency in September amid intense criticism of his own performance after Katrina, the August 29 storm that left more than 1,300 dead in Louisiana and Mississippi.

"It appears to me that, you know, when Chertoff does things like tells me that I've got to go to Baton Rouge and plop my butt down on a seat in Baton Rouge and run a disaster from there, I think that shows naivete about how disasters are run," Brown told CNN. "And you've either have to get with it, or move on."

Asked whether Chertoff should be dismissed, Brown said, "Well, I think so." He said FEMA had been "marginalized" by Chertoff and his predecessor, Tom Ridge, and that he had expected the agency's performance to suffer.

"I had been screaming internally that the budget cuts, the personnel cuts and what they were doing within Homeland Security was in effect marginalizing FEMA, and I predicted that at some point -- in a very specific memo to both Tom Ridge and to Chertoff -- that at some point, FEMA would fail," Brown said. "I just didn't expect to be in the middle of the failure."

The White House has stood behind Chertoff, who became Homeland Security secretary in February 2005. President Bush said Tuesday Chertoff was doing "a fine job."

But a House committee that investigated the response to Katrina criticized Chertoff for waiting two days after the storm hit to activate a national response plan -- and for naming Brown to lead the federal response, even though he was not trained to take on that role.

In testimony before a Senate committee in February, Brown said communicating with the White House through Chertoff was a waste of time and graded Chertoff's performance a C-minus. (Full story)

Chertoff days later flatly rejected the accusation that either DHS or the White House were disengaged as the storm deluged New Orleans and leveled much of coastal Mississippi. (Full story)

A videotape and transcripts of an emergency response meeting released Wednesday seemed to reinforce arguments that governments at all levels identified the potential dangers from the storm but were under-prepared for the devastation. (Full story)

On Thursday, Brown said he spoke with Bush directly "on at least a couple of occasions" on August 29 and told him about the failure of New Orleans' levees -- "Because that, again, that was almost foremost in my mind and my concern."

In a briefing the day before Katrina made landfall, Bush was told by National Hurricane Center Director Max Mayfield that Katrina might send water rushing over the tops of the levees and leave New Orleans flooded.

In an interview September 1, three days after landfall, Bush said, "I don't think anyone anticipated the breach of the levees."

Brown defended his former boss' statement Thursday, saying Bush had been told the storm's intensity had decreased after landfall.

"I was still worried about it, because I knew what the potential was," Brown said. "But I think the president was speaking honestly at that point that he didn't really anticipate that they would be breached because of all this conflicting information."

White House spokesman Trent Duffy said he could not discuss Bush's "private conversations" and would not confirm anything "either way" about whether Brown had discussed the levee breaches with the president.

But he said the government had helicopters in the air quickly to help rescue people trapped in the flooded city.

DHS official resigns

Also Thursday, the DHS director of operations and a key figure in overseeing the response to Katrina announced he will resign effective March 31.

A DHS spokesman said the official, Matthew Broderick, wants to spend more time with his family.

Last month, Broderick admitted during testimony before a Senate panel that he went home hours after Katrina had made landfall without first alerting Chertoff to reports that levees had breached in New Orleans.

Those reports included an account from a FEMA official who witnessed a breach.

Broderick said the reports from the field were conflicting and he didn't want to pass along "rumors" to his boss, who praised him Thursday.

"Over the past three years, Matt made tremendous contributions to our homeland security, having planned and coordinated countless national security events and intra-agency activities," Chertoff said in a written statement.